


vault 71

by Madfalldyn



Series: Commissions [127]
Category: Fallout (Video Games)
Genre: Alternate Universe, Breeding, Creampie, Dubious Consent, F/M, Human Experimentation, Incest, Multi, Parent/Child Incest, Shotacon, Sibling Incest, Underage Sex, Vaginal Sex, commission
Language: English
Status: Completed
Published: 2021-03-18
Updated: 2021-03-18
Packaged: 2021-03-27 20:13:59
Rating: Explicit
Warnings: Rape/Non-Con, Underage
Chapters: 1
Words: 8,010
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/30128220
Author URL: https://archiveofourown.org/users/Madfalldyn/pseuds/Madfalldyn
Summary: One of many of Vault-Tec's questionable experiments, Vault 71 is populated by two boys, and hundreds of women. How will they manage to survive, and sustain their population in the future?
Series: Commissions [127]
Series URL: https://archiveofourown.org/series/1845484
Kudos: 17





	vault 71

Vault-Tec sure knew how to sell survival up on a silver platter. It’s amazing how well Vault 71 held up, considering the destructive forces that swept across the United States as the bombs fell. Overseer Kate Rose is surprised, to be quite honest, that any of this is real. It’s been a wild adjustment from her everyday life, to a life underground. 

The bunker is located beneath a kindergarten school, though that doesn’t really seem to be either here nor there. It doesn’t matter where it is, when the bunker is one of the few options to survive the nuclear fallout that would come about from war with the Chinese.   
So many people bought their way into this bunker, just like so many others, but most never thought things would really come to this. Nuclear war was always a possibility, sure, but who thought the world would actually tear itself apart like this? Of course, the secretive nature of Vault-Tec doesn’t really show itself until everyone has filed inside, and roll is called.

“What do you mean that’s the population?” Kate asks, as one of the scientists in charge of taking census reports to her.

“I’ve checked over things multiple times, and I think many of us noticed as we were filing inside, but those numbers are correct. There are only two male residents of Vault 71, and that lines up with the roster we were given,” the scientist answers, and Kate places a hand on her face, trying to fight the urge to scream.

Her job is to see that the Vault survives and thrives long enough to serve as a sort of capsule, protecting the residents until the outside world is safe enough to venture back out. But how are they supposed to survive long enough for the fallout from multiple nuclear detonations to finally clear if they can’t even keep their population going?

“Two men? That's it?” Kate asks, again, and the scientist responds.

“Yes, ma’am, that’s it. And, truth be told, they’re all quite young,” the scientist answers, and Kate feels her blood pressure spiking even higher.

“Really? What in the hell were they thinking…?” Kate asks, to no one in particular.

She knew she would be the overseer here, and accepted that responsibility as an honor. She read over her duties time and time again, taking them very seriously, but nowhere in her manual did it mention a possibility like this. Hundreds of women, and only two boys? The numbers were supposed to be fairly close, with men and women in almost equal numbers, allowing for plenty of coupling so that the population could thrive and both sustain itself, and grow to match the extra space the Vault offers.

She can’t help but be frustrated, and feel lied to. Of course, she couldn’t have known that Vault-Tec wanted to more or less treat the Vaults as controlled experiments, to see just how humans would react to impossible situations in the face of apocalypse. It’s not looking good for her, so far, but she isn’t going to just give up easily. Sure, things look grim, but don’t they have time to figure something out?   
It’s going to take a while for the women within the vault to surpass child bearing age, after all. Perhaps they can wait for the boys to mature a bit, maybe that would be a possibility. Naturally, however, she was chosen for leadership, and not for scientific achievement.

“Alright, well, you have the brains and the computers. Can you run some simulations? Show how things might pan out if we give those boys some time to mature. If we play our cards right, would it be possible to set up shifts of some kind, and use them to keep a sustainable population that we could grow over time?” Kate asks, and the scientist pauses for a long time.

“I don’t know how I feel about that line of thinking,” she responds, and Kate can’t help but grow more frustrated.

“I’m not going to fail the people within my Vault. I didn’t ask for your opinion, I just want numbers, okay?” Kate orders, hanging up the phone.

Two boys. How in the world is she supposed to Oversee a vault like this? Was this some sort of clerical error, or is whoever designed this program a monumental idiot? Sure, she might have survived the initial blasts, but what good does that do her if she’s trapped in a tin can, sure to die out without leaving any legacy behind her? It’s too much to bear, and Kate refuses for this to be the end of vault 71.

~X~

“It isn’t possible,” the scientist explains to her, crushing her dreams in an instant. “The timeline would be way too close, we’d be pushing it even if we waited the bare minimum for them to be sexually developed. There are simply too few of them, and too many of us. Without some substantial changes to their genetics, there’s just no way they could have high enough output to sustain the population. The children we’d have would take too long to develop, and we’d be out of luck.”

“And you’re sure about that?” Kate asks, burying her face in her hands. “Absolutely certain?”

“I can send you the reports, but it’s not going to make any difference. I’ve had the computer running every single possibility, and it is not looking good.”

“How in the hell are we supposed to get out of this mess? It’s going to be decades, at least, before the surface is even remotely safe, and we have to survive down here with no hope of a future? If I explain that to everyone, there’ll be a riot.”

“Likely, yes. People aren’t going to take kindly to finding out that the future they bought for themselves and their descendants was nothing more than a lie,” the scientist says, more musing aloud than offering anything constructive.

“I know that, and I have to find a way around this. There’s already talks, questions. People are starting to piece things together. If we don’t have a solution for this soon, the security forces aren’t going to be enough to contain what happens. Hell, I wouldn’t be surprised if they’re just as frustrated by all of this.”

“I understand, but I’m not entirely sure what you expect to be done about this. Like I said, short of altering the boys completely, there’s no way they’re going to be able to fertilize anyone yet, and we would need to begin soon if we were going to have any chance of-” the scientist begins, and Kate suddenly has a realization.

“Wait, ‘short of altering the boys,’ you keep bringing this up, but what would that entail, exactly?” Kate asks, and the scientist pauses for a moment.

“Well, there are ways we can modify their development, but it would likely have unintended side effects and isn’t something I can ethicall-” the scientist explains, but Kate cuts her off once more.

“I don’t care about ethics, here, I have a Vault full of panicked and angry women, that feel like they were sold a bum ride. I need answers, solutions, and I don’t care how ethical they are,” Kate explains, and the scientist is silent for several moments. Kate doesn’t know what’s taking her so long, but she’s not about to compromise her stance by saying anything else.

There’s nothing else to say, anyway. Her point is firm, and absolute. There’s no other choice if they’re going to have a successful vault that can endure into the future, and Kate isn’t going to let some clerical oversight lead to the failure of her vault.

“Alright, I’ll crunch the numbers on that,” the scientist agrees, eventually. “But it’s going to be a lot of ifs, I just don’t know how things wi-”

“Just do it,” Kate says, and the phone clicks into its cradle. Finally, some hopeful news. The Overseer has been staring at these files for so long now, trying to think of some way out of this hellish scenario. Lately, she’s been eyeing the photos of the two boys that are such a conundrum to begin with, and she can’t help thinking they’re a bit cute. Appealing, even.

She shakes her head, that’s gotta be her nerves talking. Been way too long since she had a man, and that’s all it is. It might not be the best solution, but if they can figure this out, these boys are going to be very busy, indeed.

~X~

“It would work,” the scientist says. “But, ma’am, I’m still not so sure about this. We’d be breaching several ethical lines here, and we’re not sure how the offspring would turn out. It’s a bit of a leap of faith, don’t you think?”

“We can open that up for discussion. It should be something we all decide on, either way, don’t you think?” Kate says, earning herself silence as a response. “It doesn’t matter, we know it will work, right? At least in theory? That’s enough to go off of for now. People just keep asking how we’re going to get through this, and I have to have some hope to offer them soon.”

“Yes, it would work. If they can start breeding with us within the next several weeks, then everything would flatten out eventually. We could have a bustling population,” the scientist explains, and Kate claps her hands together.

“Good enough for me, I’ll call together a meeting, then.”

~X~

“Alright, ladies, this is something I’ve needed to explain to you for some time now, and I’m sorry for keeping you all in the dark. I don’t know why Vault-tec decided to do things this way, what reason they could possibly have for this sort of distribution, but we’re alone down here. We have to solve our own problems. As many of you have likely noticed, the bulk of us are women. There are only a handful of men, and I use the term ‘men’ very loosely here. In truth, they are boys, and nothing more. They are too young to reproduce, and by the time they are ready, even if we were to go through intense conservationist efforts and planning, we would be hard pressed to survive this situation long enough for the surface to be safe for us,” Kate explains, bracing herself for rage from the audience.

“What do you mean? We’re going to get old and die down here, with no chance to carry on our legacy?” one woman asks, and she is soon followed by a chorus of similar sentiments. Just as Kate expected, her Vault Dwellers are pissed. It only makes sense, given the terrible situation they’ve found themselves in, by no fault of their own.

“I know, it’s a horrible situation, and I’ve only been hiding the truth from you while I attempted to find a solution to it. We can’t carry on like this, without hope and order the society we’re meant to be preserving down here will collapse, and we’ll be little more than beasts!” Kate explains, pausing for effect as the silence of the crowd lingers in the air. “But, we were given a great many tools. We have a way to escape this fate, if you will all bear with me. I wanted to bring this to a vote before making a final decision. I have with me a scientist, one who believes we can solve our problems, if we bend our ethics a bit. Please, hear out Natalie, and let her explain things to you.”

“Good evening,” Natalie begins, stepping up into place beside Kate. They’ve been working closely together now, planning how to bring this topic to the attention of the Vault, and Kate insisted on having Natalie explain the science herself. It would be better, she believed to have people see who their savior would be directly, if all of this actually pans out. “I know Kate has given you the basic information here, but I wanted things to be very clear before we move forward with this plan. It’s not ideal, pretty far from it in fact, but we can’t rule any possibility out, not when we’re in such dire straits.”

“Get on with it!” someone in the crowd yells out, and Kate glares at them.

“Please, be civil. This is an open forum, yes, but we are trying to explain things here,” Kate says, before gesturing for Natalie to continue.

“Thank you, so, we have the ability to alter the boys genetically. I know that sounds like a lot, but it’s the only way we’re going to be able to sustain our population. We just need to tweak them a bit, to make it where they can fertilize us despite their young age, and we’d be able to get through this,” Natalie explains, doing her best to hide how much this idea bothers her.

Kate has told her time and time again that this is for the good of the Vault, that worrying too much about what’s right or wrong would only lead to further problems down the line. Of course, the more things are explained, the more the audience grumbles.

“You mean our only choice is to have sex with a bunch of kids?” someone finally asks, breaking the tension that has been building up.

“Yes, that is the only way we’re going to be a successful Vault,” Kate says, her tone short, and firm.

“That’s ridiculous, can’t we just wait for them to grow up? Even that seems like a bit much, but I guess I can kind of understand,” one of the women in the audience asks, and Natalie shakes her head. 

“I had the same thought, at first, but after running the numbers and simulations, there’s no way it would work. We just don’t have the numbers for that, we have to start as soon as possible if we’re going to get through this. In an ideal situation, with the population an even 100 to 100, as Vaults were intended to be, we would already be starting out with couples matching up and reproducing. We’re a bit behind schedule.”

“Schedule? For something like this? That’s insane!” an older woman cries out, obviously annoyed by all of this. “We bought these spaces down here to live our lives, not to be forced into some freaky experiment.”

“What good does arguing do now? I’m taking this to a vote, but this is the only way we’re going to be able to succeed. If we don’t do this, the human race has one less Vault to rely on. What if the others didn’t make it? What if we’re the only ones who survived the bombing, and we die out completely because we were afraid to take this risk?”

“Kate does make a fine point. With all the radiation on the surface, we have no way of contacting other Vaults. For all we know, we’re the only survivors, and letting this setback go might spell the end of the human race.”

“Would that really be so bad? I mean, hell, if we have to modify and fuck a bunch of innocent kids just to keep our race alive, maybe we should just give up?” Someone says, and some others have the same line of thinking.

Of course, they’re soon drowned out by others, shouting them down, explaining how irresponsible that line of thinking is. In the end, the forum dissolves into arguments, and fights, and Kate does her best to keep order until it is time to vote.

“Alright, alright, we’ve all discussed this back and forth for some time now. I don’t think anything anyone else says is going to change any minds, right? So, let’s get this over with and vote already, okay?” Kate says, and while the crowd grumbles for a moment, they ultimately agree with her.

Kate has everyone submit their vote, wondering just how things will play out. She hopes she and Natalie were convincing enough to get a majority on board, knowing it is their only hope of making it through this sabotaged Vault they’re stuck with. As they tally the votes, counting them painstakingly, Kate wonders if she shouldn’t rig things.   
She is the Overseer, after all. Her word is law down here, and if she were to alter things a bit and make sure her motion passes, it would be for the good of everyone down her. Beyond that, even, for all the lives lost who worry the human rice might have died off with them. ‘

For now, she decides to wait. She’ll get the results before anyone else, and if she doesn’t like it, she can always just lie about it. She takes the votes to her office, eager to tally them and see what choice her people made.

~X~

It doesn’t take her long to count up the votes, and by the time they’re all in, Kate is shocked. Her plan won by a pretty substantial margin, a large enough one that no one would question it or ask for a recount. She knows that’s good, that too many people worrying about the validity of this choice would only lead to further problems down the line.    
Sure, people are a bit reluctant to do this, but that’s understandable. In the end, most have chosen the future of the human race over their own apprehension, something Kate had been counting on. She doubts they’re the only Vault to survive this, as much as it might be obvious now that Vault-Tec was having some problems in their planning stages, there’s no way they messed up every group they sent below ground this badly, right?

Kate is just glad to see that she can move forward, and reaches for the phone with a smile on her face. She calls the science lab, eager to speak with Natalie and get the ball rolling on their salvation. It’s a hard choice, but this is the Overseer’s job, is it not? She has to make the hard calls, and make sure her people and her Vault are successful. She glances at the pictures of the boys she’s pinned all of her hopes on once more, finding herself looking at them with favor now. They’re going to be the solution to this problem, and she’s glad that she was able to navigate things so well.

~X~

Of course, the real work now falls to Natalie. She has to actually perform the experiments, with the help of her team. They have to modify the two boys, making them fit to breed far earlier than expected. It’s not difficult so much as it is time consuming, and even once they’re done, they need to perform extensive testing to insure the changes took.

“So, we’re glad to have you here today, but… you’re sure you don’t mind going forward with this test?” Natalie asks, looking at the woman before her. She’s a younger girl, and it’s a surprise that she would leap at a chance like this. In truth, she was one of the first in line.

“I don’t mind at all,” she says, smiling. “I’m kind of looking forward to it, honestly, it’s been pretty boring down here.”

“Well, uh… alright, I’ll note that response!” Natalie says, hardly able to believe what she’s hearing. This girl is really leaping at the chance to sleep with these boys just because she’s bored? Being down here is a bit lonely at times, but come on. With that out of the way, the door to the testing chamber whooshes open, and the girl is ushered in.

Given the state the boys are in, it’s almost like putting a meal before a starving animal. Of course, they took the liberty of having the girl strip down first, adding to the effect. After all they’ve been through, the boys’ sex drives have been ramped up substantially. As soon as they lock eyes on the beautiful young woman strolling into the room they’re being kept in, it’s over for them. 

Natalie has had quite the time even caring for the boys, as time has gone on. The more the experiment took hold of their development, the more ravenous they became. Even sending in an assistant with some food would often lead to them growing hard, begging her to sleep with them. This will be the first time anyone has actually obliged to that, however.

“Oh, wow, they’re really packing,” the young woman says, a bit surprised. She’s excited, though, Natalie can see that from the look on her face alone. The boys rush over to her, already reaching up to touch her, stroking along her legs, her thighs.

“Please, don’t push them too far or anything,” Natalie says, pressing a button to activate an intercom in the testing room. “They’re inexperienced.”

“Don’t worry, I’ll be gentle,” the woman says, leaving Natalie wondering just what it was she was doing before coming into the Vault.

Sure enough, she seems to have a good handle on the boys already. She kneels down in front of them, reaching down and taking each one in hand.

“I bet you’ve been feeling pretty funny, huh? Being poked and prodded and experimented on… but my, my, look what it’s done to you,” she says, as she begins pumping her hands up and down their lengths.

This might be going a bit  _ too _ well for an experiment, but Natalie supposes asking for volunteers would have been bound to lead to someone like this, wouldn’t it? The more she watches, the stranger she begins to feel. She can’t help fidgeting in her seat as this woman handles the boys with expert precision, watching as their faces shift with the pleasure she grants them.

“So, you need to see what they’re capable of, right?” the woman asks, and Natalie presses the button once more.

“Yes, that’s the plan. They need to be able to reproduce, after all,” she explains, and the woman nods. Without a word, she rises, crossing to the bed in the center of the room. The boys follow after her, desperate for more attention from her. They babble on about how good that felt, how they still feel funny, and she shushes them, explaining that she’s going to make them feel better soon enough.

Once she lays on her back on the bed, spreading her legs and sprawling out, the boys are on her in an instant. She guides one in between her legs, helping him line his cock up with her cunt. Of course, she’s soaked by now. The very idea of helping these boys learn about this sort of thing is thrilling her, especially with how long it’s been since she had cock in her.

The other boy is fidgeting, looking confused, and she reaches out to him. The first boy is already pounding into her, fucking her cunt as hard and fast as he can manage, desperate to get relief for the strange feelings that have been building up within him for days now. This one will need a way to distract himself as well, and the woman guides him up onto her stomach, working his cock in between her breasts. Soon, she has both boys eager to fuck her in whatever way she guides them. The first is slamming into her cunt, making excellent use of that huge cock, while the first is fucking her breasts. She loves the feeling, watching them as they groan, losing themselves completely in her body.

“Oh, you’re such good boys, you know that?” she praises them, reaching down to pat one on the head. “You’re going to be so good at this, I can already feel it.”

“I take it they’re uh… performing satisfactorily?” Natalie asks, feeling as if she’s interrupting something. The worst part of all of this is how this is affecting her. She’s watching this woman teach these boys to fuck, wondering just how far she’s going to go with this, and just how far she must have gone in the past. In the end, Natalie would rather not admit just how damp her panties are getting from this display.

“They’re wonderful,” the woman says, looking right into the window Natalie watches her from. “This is the most fun I’ve had in years.”

And sure enough, she does look to be having fun. Each of her moans and whimpers are punctuated by the boys ramming into her, or between her breasts. It doesn’t take them long to reach their peak, coming for her in a matter of moments. When they come, the first fills her up happily. She holds him in place, waiting until every drop rushes into her. The other boy’s come ends up covering her face, and her breasts, and the excitement of it all is enough to have her tensing up, coming as the boys use her.

In the end, she goes for several more rounds, and the boys seem inexhaustible. It’s an unexpected side effect, but probably for the best, and Natalie notes that down happily. She’s a bit disturbed by just how much this woman seems to enjoy herself, but the more she watches, the more she understands.

  
  


~X~

“There are some side effects, it would seem,” Natalie says, and Kate can’t help but groan.

“If this is more bad news, after all the setbacks we’ve had, I’m not going to be happy,” Kate says, and Natalie is quick to explain.

“No, no, I don’t think it’s going to be anything serious. The first few test subjects seem to have taken well to the experiments, and the boys are still doing fine, it’s just… well, they were absolutely ravenous. They each went with their paired mate for hours before finally wearing themselves out. It’s not like anything we’ve seen before, honestly,” Natalie explains, still sounding a bit shocked about all of it.

“Well, isn’t that a good thing? As long as they can actually get them pregnant, an appetite like that seems to be a good thing, doesn’t it?” Kate asks, and Natalie hums in approval.

“I think so, yes. There’s no telling what kind of other effects the experiments might have had on the boys, though. This could be one of many, and only time will tell if these carry through into their offspring. In fact, we might have to do these experiments again in the future to improve our chances of success,” she continues, but Kate is already tuning her out. There’s really no point to speculating that much, by the time they’re worrying about all of that, it’s likely to be another Overseer’s problem either way.

“We’ll cross those bridges as we come to them. No real sense in waiting, right? Let’s move on to the next phase,” Kate says, already deciding to continue her plans. It’s going to work, and there’s really no point in debating things further. While the vote might have been hesitant, passing by very narrow margins, she’s sure that this is the only way forward. Sure enough to stake her own reputation on it, in fact.

~X~

“The experimentation seems to have been a success,” Kate announces to the entirety of Vault 71. “So, we’ll be moving forward with the program. You’ll be receiving assigned shifts soon enough, and I’m sorry to say, they’re not optional. If you are of child bearing age, you will be given a time slot with one of the two boys, and you will be impregnated by them.”

Absolute silence follows that announcement. Many of those who voted in favor of this plan were assuming it would be on a voluntary basis, that only some of them would have to be bred by these children, and coming to find that that is not the case is a bit of a shock to them. But, Kate continues.

“It’s going to be rough, especially as so many children are born around the same time, but we’re going to get through this together. Remember, this is for the sake of humanity itself. We’re having to do some unsavory things, to be sure, but people are going to thank us for this sacrifice someday. We’re going to be lauded as heroes for generations to come, the very saviors of the human race!”

Her words don’t do much to ease the building tension, but in the end, the security force is behind her and Kate’s reasoning is sound enough to make people swallow this pill no matter how much they may not want to. As time goes on, each and every woman within the Vault that is fit to bear children has their time with the boys, and even their rampant sexual needs are met for a time. The side effects prove to be even more severe than first expected, as the boys show no sign of being truly exhausted even as days go past of near constant fucking.

~X~

“You’re sure you want to go this early on?” Natalie asks, and Kate nods.

“It’s not your job to question me, you know,” she adds, and Natalie is a bit shocked.

“Yes, but, there’s still so much we don’t know about this. Sure, some of the early test subjects are pregnant now, but that doesn’t mean-” Natalie stops, as soon as she sees the look on Kate’s face. She’s spent a long time looking at the pictures of these boys, even coming down to watch a few of the early sessions herself. Natalie can see now that this goes beyond anything normal. She’s got some sort of desire to do this with them, to be intimate with them, and Natalie finds herself faced with similar feelings to that first test, with the strange woman that has tried to come back many times since being impregnated. There’s no point to her being with the boys, but she still tries.

“I just said, I don’t expect any questions from you, alright?” Kate says, shaking her head. “I don’t have to explain myself, but I’m the Overseer. I’m going to be one of the first, as a sign of solidarity with the rest of those stuck in this Vault. I want them to know I’m not exempt from this, that I’m going to be doing my part for this plan as well.”

“Of course, ma’am,” Natalie says, though she can’t help but wonder how long Kate rehearsed that little speech in the mirror. Not many others would guess at just how obvious her intentions are, but Natalie is pretty sure she’s right on the money.

“Alright, well, let me in the chamber,” Kate orders, and the door whooshes open. It’s a far cry from that one testing chamber, now. The lab has been changed out for more opulent bedrooms, with each of the boys having one of their own. It’s a rather nice room, and they have no end of toys and other items to amuse themselves with whenever they’re not doing their part for the Vault. Of course, with Kate entering in to one of the rooms, the boy’s attention is immediately on her.

“Oh, my, look at how cute you are,” Kate says, as the door shuts behind her. Another change is that now, the women have their privacy with the boys. Now that Kate is alone with one of the children she’s been watching over for so long, she can be open about just what planning all of this has done to her. “I’ve been wanting to meet you for so long now.”

“Hello!” the boy says, already reflexively undressing. He knows exactly what Kate is here for, as it’s become habit by now. The process has only been going full force for a few days now, as they try and fine tune just how much the boys can handle at once. Kate wanted to be one of the first, but her busy schedule meant she had to take a few days to make it down here.

“You seem eager, now, don’t you?” Kate says, eyeing the boy’s cock. She’s seen this go down plenty of times, wanting to personally observe some of the sessions in the experimental phase, and it was so annoying having to hide the effect the boys had on her. She’s become somewhat obsessed as time has gone on, and so far, she’s been able to keep that under wraps. But now, with this boy before her, she can’t help stripping down. She wants to feel his cock inside of her, slamming into her and filling her up before he finally knocks her up.

“It’s a lot of fun, getting to be with whoever comes in!” the boy says, his innocence in the face of this bizarre situation somehow heartwarming.

“Oh, I’m sure it is,” Kate says, kneeling down beside the boy. She can’t take her eyes off of his cock, far larger than it should be at his age. “I’ve been waiting to have some fun with you myself. I’m the Overseer here, you know, so it’s me you have to thank for all the fun you’ve been having.”

“Wow, really?” the boy asks, grinning up at her. “I definitely want to have lots of fun with you, then!”

“Don’t worry, we will,” Kate says, as she picks the boy up. It’s easy for her to hoist him up onto his bed, and kneel down beside it. She wants to take her time, to really savor this, so she’s not going straight into the sex. Most women she’s known try to get this over with as quickly as possible, doing it more as a service than anything else, but Kate thinks she might as well enjoy this. It’s been too long since she’s been with a man, either way.

She leans in, pressing her lips to his cock, and slowly parts them. It doesn’t take her long to find her rhythm, to begin working her way up and down the length of his cock. It’s a good feeling, looking up at the boy as he gasps and whimpers. She knows he’s felt a lot of fun stuff these past few days, but she hopes this is a bit more exciting. She wound’t be entirely surprised if she’s the first one to go this route with him, to use her mouth to get him off.

Despite all the fun the boys have been having, it hasn’t done much to improve their endurance yet. After only a moment of sucking him off, the boy finds he can take no more. With a soft groan, he comes, his seed spilling into Kate’s mouth. She swallows it gladly, eyes still staring up at the boy. Some might worry they’ve wasted their chance, but she knows that was only the start of the fun she can have with this boy. Sure enough, when she pulls back he’s still completely and totally hard.

“Alright, it’s time for you to knock your Overseer up!” she says, as she climbs onto the boy’s lap. 

~X~

Of course, that is only the beginning. Time passes, and the experiments continue, until nearly everyone in the Vault is with child. It took several sessions for some women, so not everyone is due at the exact same time, but it’s close enough to make things difficult.

Kate is, of course, one of the first to give birth considering how early she went through the process. At first, it seems that everything is going well. The children they carry come to term perfectly, and there don’t seem to be any sort of birth defects, or disorders that are obvious. Even when they have impregnated their own family members. Sisters, even mothers, of the boys show no signs of birth defects in the children they bear.

~X~

“It’s a bit strange, seeing you like this,” the woman says, blushing at the sight of her son. She’s been putting this day off, as much as she did want to see the boy she had been raising before he was comandeered for the Vault’s survival program.

“Hey, little bro,” his sister adds, as well. It’s rare that the scheduling allows for two women with one of the boys, but with a mother still in child bearing range and a sister just entering it, it was an opportunity Natalie couldn’t afford to miss out on. Especially considering even family members seem to show no ill effects when carrying the children from their relatives’ seed.

“Hey mommy, hey big sis!” the boy says. It doesn’t seem to matter that they are his sister and his mother, he gets just as hard for them as he would for any woman who enters his room. “Are you here for the usual fun?”

“Yes, we are, sweetie,” his mother says. She’s a bit torn up by all of this, but she’s doing her best to put this in the right fram of mind. This is her son, and he’s been twisted and shifted by these experiments, but he’s a hero. Not only is he going to be the herald of a new future for this Vault, he might very well be one of the few hopes the human race has! She can bear anything, if it means her son is that much of a hero. “You’re such a good boy, saving us all like this! My little hero!”

“Mom, you’re laying it on a bit thick,” her daughter says, rolling her eyes. “Come on, let’s get this over with.”

“You want to go first, then?” her mother asks, and she nods. 

“Sure, why not,” she says, waving a hand dismissively. She’s pretty chill about the idea of fucking her brother, and simply hops up into bed. “Come on, little bro, you’re supposed to knock me up, right?”

“That’s your own brother, young lady!” her mother chastises, and the girl rolls her eyes once more. 

“This is what we’re supposed to do, isn’t it? It’s not a big deal, come on,” she says, and her brother seems to be of the same mind. Of course, given how mad he is with lust, it doesn’t matter who the pussy he’s going to fuck belongs to. He tries to hop up into bed, but his mother is quick to scoop him up instead, helping him up.

“Do you want mommy to help?” she asks, and the boy pauses for a second. Of course he doesn’t  _ need _ her to help, by now he’s done this countless times, but he nods anyway. She takes up a spot behind him as he lines himself up with his own sister’s cunt. He’s played with her so many times in the past, before they came into the Vault, even some before this experimental breeding started. But now, he’s looking forward to playing the new game he’s learned. The game that some women seem to love, while others seem to dread.

His sister is somewhere in the middle, simply going along with things as they happen. He pounds into her, feeling a bit more of a thrill to be inside of her than he has the other women. She’s not a stranger, like them. He’s used to playing with his sister, to having fun with her, and this is just more of the same.

“That’s my good boy, fuck your sister, knock her up!” his mother says, from behind him. As he fucks her, she’s gently guiding him, murmuring to him as she watches.

“Mom, come on, you’re making this weird,” the daughter says, but she doesn’t stop. 

“That’s right, that’s mommy’s good boy…” she murmurs, working her son to a higher and higher pace. He seems dead set on finishing inside of his sister now, even more determined than usual. In the end, when he finally does come, his seed spills into her. The warmth that floods into the daughter is enough to break down even her icy calm, forcing her to come from her brother filling her up.

“Now, it’s my turn!” his mother says, already shifting him onto his back. She opts to take the lead, pouncing onto the boy and riding him. Given the way the experiments have changes his physique, he’s ready for her in an instant. As his mother rides him, she speaks to him continuing in the same vein she was while he was fucking her daughter.

“Such a good boy, knock mommy up, be the hero I know you are!” she says, every bit of her apprehension fading as she gets into riding her son’s cock. She knows this is wrong, she knows she shouldn’t never be doing this, but she has no choice, right? She might as well enjoy this, right? Her son certainly seems to enjoy it, so why shouldn’t she have just as much fun as he does?

She rides him until he finally comes, and sinks down onto him letting his seed spill into her. She knows he’s going to knock her up, she can just tell, and she savors the warmth of his seed as it fills her up.

~X~

  
It isn’t until years down the line, when each of the women have had several children by this method, that things start to get a bit weirder. They’ve long since crunched the numbers, finding that the ratio of births is about 4 to 1 when it comes to female to male. It’s not ideal, considering how badly they will need more males to continue this program in the future, but the residents of Vault 71 are able to run up enough simulations to make things work.    
But, that isn’t the end of the repercussions of their experiments. Not by a long shot. As time goes on, the girls that are borne of this method grow up with no real issues. They do seem a bit different, once they reach maturity, with more developed bodies that are perfect for breeding, but it’s the boys that really show some differences.

Much like their fathers, who seem almost frozen at the state they are in, they only grow to about the same age and then seem to stop. They can still breed, just as their fathers before them did, but it’s a bit of an eccentricity the women will have to get used to. In the end, it does seem like Vault 71 will be able to overcome their population issues, though it’s going to be a lot of getting used to, and a very strange offshoot of humanity that eventually walks out of the vault and into the new world.

~X~

It’s been generations since those who set the Vault on this path have passed on. Their children’s children now carry on that legacy, as the Vault continues to survive and swell. They’re still maintaining their size, mostly, not trying to go above their means here. There’s only so many the Vault can hold at once, and the scientists of this time keep a close eye on that number.

They have to, as the women of this society have come to almost worship the boys that are so rare among them. Any time a male is born, he is destined to have a life of luxury. Being fairly rare, the boys that are born and stay boys forever are precious, to say the least.

The side effects of the experimentation done to preserve the life in this Vault are pronounced, and one look at the women who now surround one of their precious boys makes that obvious. They all have shapely proportions, ideal for bearing children, while the boys are used nigh constantly by them. It’s all to keep things going, to ensure the Vault has a bright future.

After all, they might very well be humanity’s last hope.

As years went on, the focus on preservation has grown more and more important. Those in charge continue to keep their focus inside the Vault, not really caring if the outside world is ready for new life yet or not.

Why should they care, when they have their own needs to meet? The boys that are born may live in the lap of luxury, but they are almost constantly exhausted, as well. The numerous women in the Vault use them constantly, outnumbering them greatly even now. It’s been so long since those first two boys knocked up as much of the Vault as possible, but those same traditions carry through to this day.

In fact, it’s become a part of the culture here. The boys are ready for breeding so much younger than they should be, and the women make the most of that. They all get their turns with the boys, the heroes that will keep the Vault alive, and they show how appreciative they are by using their bodies to practically worship them.

It’s a far cry from the apprehension the women once felt at the idea of using the boys to prolong their existence, and the boys definitely don’t seem to mind. The near-constant orgies they experience are simply a part of life for them, the same as anything else.   
If this society they’ve formed ever does rejoin the world at large, it’s going to be a strange reunion, to say the least.

~X~

Right now, a group of women have all booked a room with one of the boys for several hours. The population is moving along just fine, so they’re not able to actually attempt to be knocked up right now, but that doesn’t mean they don’t get to have their fun with the boy. It’s almost a commodity at this point, getting some time with one of them.

The women coo and dote on him, each waiting for their chance to ride him, to suck his cock, to toy with him. It’s a long process, but the boy is just as durable as his progenitors. No matter how much he has to work to pleasure these women, it seems like he’ll never get tired. Every time he comes, his seed covering or spilling into one of the lovely women using him, the boy is ready to go in a matter of minutes. 

“That’s our hero, our good boy!” the women always coo, and the boy can’t help but smile as they all dote on him. He has never known anything but this constant pleasure, and it’s all he will ever know. There’s never any lack of women wanting some time with the closest thing this Vault has to men, and using them is becoming more of a service than anything else.

Outnumbered as they are, that’s really the only way things can work. Right now, this boy isn’t the only one in use. In all the rooms here at the Vault’s lab, each boy in the Vault is seeing the same treatment. Outside of meals and sleeping, the boys are fucked almost constantly. There’s hardly ever a lull, as anyone who isn’t working or otherwise indisposed is happy to spend time with the boys.

At this point, nearly everyone in the Vault is related, even if distantly. The more they breed, the less issues there seems to be with that. Now, it doesn’t matter who a woman can line up time with, they’ll take it without a second thought. Mothers will gladly enter into the room with their son, eager to ride him and fuck his brains out. Sisters will go with their brothers, and even book rooms in groups. It doesn’t matter, they do things so differently here that none of this is looked at with a second thought.

It’s hard to say if Kate or Natalie would be proud of the legacy they left behind, making the choices they felt that they had to, but it’s too late for anything to matter now. What’s done is done, and this Vault found a way to survive. To thrive. Even if it might be a bit bizarre. No one in the Vault thinks so, at least, and they hardly know the past they left behind when Vault-Tec started this particular experiment.

**Author's Note:**

> If you're interested in my writing, check out my Twitter for updates and information! https://twitter.com/MadfallWriting


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